NAME¶
glFrontFace - define front- and back-facing polygons
C SPECIFICATION¶
void glFrontFace(GLenum mode);
PARAMETERS¶
mode
Specifies the orientation of front-facing polygons.
GL_CW and GL_CCW are accepted. The initial value is
GL_CCW.
DESCRIPTION¶
In a scene composed entirely of opaque closed surfaces, back-facing polygons are
never visible. Eliminating these invisible polygons has the obvious benefit of
speeding up the rendering of the image. To enable and disable elimination of
back-facing polygons, call
glEnable() and
glDisable() with
argument
GL_CULL_FACE.
The projection of a polygon to window coordinates is said to have clockwise
winding if an imaginary object following the path from its first vertex, its
second vertex, and so on, to its last vertex, and finally back to its first
vertex, moves in a clockwise direction about the interior of the polygon. The
polygon's winding is said to be counterclockwise if the imaginary object
following the same path moves in a counterclockwise direction about the
interior of the polygon.
glFrontFace specifies whether polygons with
clockwise winding in window coordinates, or counterclockwise winding in window
coordinates, are taken to be front-facing. Passing
GL_CCW to
mode selects counterclockwise polygons as front-facing;
GL_CW
selects clockwise polygons as front-facing. By default, counterclockwise
polygons are taken to be front-facing.
ERRORS¶
GL_INVALID_ENUM is generated if
mode is not an accepted value.
ASSOCIATED GETS¶
glGet() with argument
GL_FRONT_FACE
VERSION SUPPORT¶
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OpenGL Version |
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Function / Feature Name |
2.0 |
2.1 |
3.0 |
3.1 |
3.2 |
3.3 |
4.0 |
4.1 |
4.2 |
4.3 |
4.4 |
4.5 |
glFrontFace |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
SEE ALSO¶
glCullFace(),
COPYRIGHT¶
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2014
Khronos Group. This document is licensed under the SGI Free Software B
License. For details, see
http://oss.sgi.com/projects/FreeB/.
COPYRIGHT¶
Copyright © 1991-2006 Silicon Graphics, Inc.
Copyright © 2010-2014 Khronos Group